(1) Field of the Invention
The present invention relates to a combine provided at the inner upper portion of a threshing chamber thereof with a dispersing guide plate for separating and dispersing grain stalks upwardly conveyed and guided to the rear wall of the threshing chamber from the lower rear portion of a threshing drum with the rotation thereof, in the direction from the central rear portion of the threshing chamber to the frontal lateral sides thereof, thus separated and dispersed grain stalks being then re-supplied from the frontal lower lateral sides of the threshing drum.
(2) Description of the Prior Art
A combine having a dispersing guide plate of the type above-mentioned has been recently developed by the inventors of the present invention and others. The provision of the dispersing guide plate causes grain stalks supplied into the threshing chamber to be conveyed as rotated by one or more revolutions around the axis of the threshing drum, thereby lengthening the treatment path. The plate also assures the separation of the grain conveyed as rotated by one revolution which is in the middle course of treatment, from untreated grain stalks supplied from the frontal center inlet. Such arrangement eliminates both excess treatment of grain stalks which are excessively rotated and conveyed in the threshing chamber, and insufficinet treatment of grain stalks which are discharged from the threshing chamber after merely conveyed a short distance along the lower peripheral wall of the threshing chamber without having been rotatingly conveyed therein. Thus, a combine of this type advantageously assures an efficient threshing with high capacity.
In treatment of return tailings to the threshing chamber for second separation, however, a combine of this type has the following disadvantages.
Like a conventional combine having no dispersing guide plate, such return of tailing is made along the entire width of the threshing chamber. Those portions of the tailings which have been returned to the lateral sides of the threshing chamber, are discharged therefrom as insufficiently treated while merely conveyed along the inner lower portions of the threshing chamber. This presents an increase in tailings and a loss in the grain discharged to the outside of the combine.
Furthermore, at the both lateral sides of the tailings return port, tailings are returned to those portions of threshing chamber where newly harvested grain stalks are rotatingly conveyed. Accordingly, these rotatingly conveyed grain stalks may close the tailings return port, or be caught in the tailings return port as if entered therein. This prevents not only a smooth and secure return of tailings into the threshing chamber, but also a rotating coveyance of newly harvested grain stalks. As consequence, the originally intended object of providing an efficient threshing by the provision of a dispersing guide plate, cannot be fully achieved.